So what is a blog anyway? Well, according to Wikipedia, "A blog (a blend of the term web log)[1] is a type of website or part of a website."
Here's their full definition.

Many wonder if they should create a blog or a web site. This is how I like to think of it...
a blog is interactive and is meant to be that way. It is a way to engage in conversations and communications. It also uses posts so every time you create a new post, the most recent post will be the first thing your viewers see.

a web site is another way to share information but it not really interactive. You are simply putting that information out there for people to view.

I chose a blog for our school library's web site. I want people to respond/comment.

Our school's web site is just that. It is a way for us to put information out there for anyone.